Light industrial circuit breaker terminal cover

This invention relates to a terminal cover for a circuit breaker for preventing electrical crossover between adjoining circuit breaker terminals. In particular, this invention relates to a terminal cover for a light industrial rated circuit breaker that can be installed without the use of fasteners and which does not interfere with adjacent mounting of multiple breakers.

Industrial-rated circuit breakers in excess of 600 volt rating, such as described within U.S. Pat. No. 5,150,091 entitled “Bus Cover and Lug Cover for a Molded Case Circuit Breaker,” are often required to become positioned next to similar circuit breakers within a common enclosure. To prevent electrical crossover between adjoining circuit breaker terminals upon the occurrence of a short circuit over-current condition within adjoining circuit breakers, the circuit breakers must be separated by a sufficient distance for electrical over-surface clearance.

U.S. Pat. Nos. 5,084,689 and 5,049,846, both entitled “Compact Molded Case Circuit Breaker with Increased Ampere Rating,” describe the use of lug cover extensions to the line end of the circuit breakers to protect the line lugs from inter-phasal faults.

The aforementioned U.S. patents describe the use of screws and the like to fixedly attach the separate lug covers to the circuit breaker enclosures at an added expense in materials, time, and labor.

So-called “light industrial-rated circuit breakers,” up to 400 volt rating, are also used within common enclosures and are separated for over-surface clearance. Low costs are achieved by utilizing single pole circuit breakers attached together with a common handle tie for simultaneous ON-OFF operation. Because of the lower costs associated with such light industrial-rated circuit breakers, the added expenses of a lug cover was heretofore unwarranted. The space separation requirement limits the number of circuit breakers used within the enclosure with a resultant limitation in

Thus, there is a need for a lug or terminal cover to be used with light industrial-rated circuit breakers at a minimum increase in cost to allow several such circuit breakers to be used in adjacent relation within a common enclosure with minimal inter-circuit breaker spacial separation.

In an exemplary embodiment of the invention, an electrically-insulative terminal cover is arranged on the line end of a light industrial-rated circuit breaker to allow a close-fit arrangement between a plurality of such circuit breakers within a common enclosure. The terminal cover is preferably in the form of an integrally formed right-angled piece having a top piece and a perpendicular side piece. The top piece comprises a pair of notches for receiving a pair of electrical conductors connecting with a corresponding pair of circuit breaker electrical terminals. The side piece includes a pair of elongated notches adapted for receiving sides of a pair of adjacent circuit breakers. A center side piece between the elongated notches can be press-fit within a combined slot defined by slots in sides of a pair of abutting side walls of adjacent circuit breakers. The top piece provides electric isolation to a top of the electrical terminals while the side piece provides electric isolation to a front of the electrical terminals.

FIG. 1 is a top perspective view of a circuit breaker terminal cover in accordance with the invention;

FIG. 2 is a front perspective view of the terminal cover of FIG. 1 in isometric projection with a light industrial-rated circuit breaker prior to attachment therewith; and

FIG. 3 is a front perspective view of the terminal cover attached to the circuit breaker of FIG. 2 .

The lug or terminal cover 10 is shown in FIG. 1 to comprise a right angle piece 12 defining a top piece 14 and a side piece 16 perpendicularly extending down therefrom. The piece 12 comprises an electrically insulative material, and is preferably integrally molded in plastic to form a one piece cover. A first notch 18 and a second notch 20 are formed within the top piece 14 on opposite sides of the center top piece 22 and with first and second end top pieces 24 , 26 at the ends of the top piece 14 thereof. The open-ended notches 18 and 20 may extend from an outside edge of the top piece 14 to a rounded end within the top piece 14 as shown. The notches 18 and 20 are preferably parallel and of equivalent size, and are adapted to at least encompass the diameter of one line conductor extending from a circuit breaker.

A center side piece 28 is formed in the side piece 16 having a first elongated notch 46 on one side and a second elongated notch 48 on the opposite side with first and second end side pieces 30 , 36 formed on the ends of the side piece 16 . The elongated notches 46 and 48 may be open-ended and rounded as described above with respect to notches 18 and 20 . The side piece 16 further comprises a first side 32 on first end side piece 30 and a second side 38 on second end side piece 36 which are indented from sides 42 and 44 of side piece 16 . Preferably the width w l , of the side piece 16 is equivalent to the width w t , of the top piece 14 where the side piece 16 is adjacent the top piece 14 . Where the side piece 16 is indented, the width w 2 is less than the width w 1 . The resultant indents 34 and 40 preferably correspond in size to a thickness of an exterior wall of a circuit breaker for providing a snug fit with a circuit breaker as will be described.

The terminal cover 10 is shown in FIG. 2 prior to attaching to the line end of a two pole circuit breaker 50 consisting of a pair of single pole circuit breakers 52 , 54 joined by rivets as indicated at 60 . The load terminals 56 , 58 are located at the bottom of the circuit breaker 50 with the line terminals 62 , 64 at the top of the circuit breaker 50 to indicate the positioning of the terminal cover 10 over the line terminals 62 , 64 . The single pole circuit breakers include a pair of operating handles 66 , 68 interconnected for common response by means of the handle tie 70 and are shown in the ON condition and a pair of line conductors 72 , 74 are connected with the line terminals 62 , 64 . The line conductors 72 , 74 extend through the notches 18 , 20 formed in the top piece 14 with the center top piece 22 intermediate the line conductors 72 , 74 and the end top pieces 24 , 26 capturing the line conductors 72 , 74 within the notches 18 , 20 , respectively.

When terminal cover 10 is attached to breakers 52 , 54 , center side piece 28 , intermediate the elongated notches 46 , 48 , is captured within the combined slots 80 , 82 formed by the slotted or grooved sides 76 , 78 of the single pole circuit breakers 52 , 54 . That is, the slot 80 on side 76 combines with slot 82 on side 78 to form a single slot in which center side piece 28 is preferably snugly captured therewithin to retain the terminal cover 10 on the circuit breaker 50 . Likewise, each notch 46 , 48 is adapted to accept a portion of sides 76 and 78 therewithin. Simultaneously, the sides 32 and 38 are preferably captured within interior sides 84 and 86 of single pole circuit breakers 52 and 54 , respectively.

The terminal cover 10 is shown in FIG. 3 attached to the two pole circuit breaker 50 with the center side piece 28 of the side piece 16 captured within the slotted sides 76 , 78 of the single pole circuit breakers 52 , 54 . The line terminals 62 , 64 are shielded in the front by means of the end side pieces 30 , 36 and are shielded at the top by means of the end top pieces 24 , 26 and the center top piece 22 intermediate the line conductors 72 , 74 . Thus, the cover 10 may be simply attached to the breaker 50 using a press fit, eliminating the need for fasteners. Of course, a snap fit is also within the scope of this invention. The slotted or notched pieces 14 and 16 allow for easy installation/removal of the cover 10 without removing any wiring. When a pair of such “shielded” two pole circuit breakers 50 are arranged side-by-side within a common enclosure, the terminal covers on both of the shielded circuit breakers contribute to added protection against any arc occurrence within either of the shielded circuit breakers upon the occurrence of a short circuit condition within either of the adjacent circuit breakers. Furthermore, the width w t of the terminal cover 10 is preferably equivalent to the width w c , of the circuit breaker 50 . With the terminal cover 10 thus designed within the envelope of the circuit breaker 50 , adjacent mounting of multiple breakers is enabled.

A simple terminal lug cover has been shown for attachment to the line end of a two pole circuit breaker by insertion within a combined slot formed within the slotted ends of the component single pole circuit breakers without requiring any additional fasteners.

While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.